This invention relates to a metal cutting tool wear indicator method and system, and more particularly to an improved cutting tool electrical signal analyzing system or process which accurately indicates progression of cutting tool wear for a timely change or intervention into the cutting process. The electrical signal components are selected and processed in such a manner that the usual sensitivities to operating characteristics or cutting conditions which vary from one machine to another are substantially minimized.
Sharp metal cutting tools such as drills, end mills, etc. have significantly different cutting process characteristics than those of dull or worn tools. For example, as a cutting tool wears, more surface area of the tool comes into contact with the workpiece. This increase in surface contact requires an increase in energy input or driving power to the tool as a reaction to a decreasing cutting efficiency. An appropriate power input monitoring system may correlate the increase in power demand for the cutting process with wear of the cutting tool and provide an appropriate signal when a predetermined power demand level is reached. However, if the monitoring system utilizes an electrical signal, a component of which is generated by the cutting tool during its cutting process, the signal may be significantly affected by changes in machine conditions such as tool type, cutter type and composition, tool feed and speed, etc. An advantageous monitoring system is one which more effectively distinguishes a tool wear signal from other machine condition signals.